RCE in Python Software Foundation Cpython
CVE-2026-4786
Mitgation of CVE-2026-4519 was incomplete. If the URL contained "%action" the mitigation could be bypassed for certain browser types the "webbrowser.open()" API could have commands injected into the underlying shell. See CVE-2026-4519 for details.
Vulnerability class: Command Injection (OS Command Injection)
EPSS: 0.003 (21.2th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L.
Affected products
- Python Software Foundation Cpython — versions 0, 3.13.0, 3.11.0
Weakness classification (CWE)
References
- cna@python.org (patch)
- cna@python.org (issue-tracking)
- cna@python.org (vendor-advisory)
- cna@python.org (patch)
- cna@python.org (patch)
- cna@python.org (patch)
- cna@python.org (patch)
- cna@python.org (patch)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Frequently asked questions
- What is CVE-2026-4786?
- CVE-2026-4786 is a high-severity vulnerability in Python Software Foundation Cpython, classified under Command Injection. CVSS score: 7.1/10. Published 2026-04-13.
- How severe is CVE-2026-4786?
- High severity. CVSS v3 base score is 7.1 out of 10.